wc1472

hey all, i have an 80s-ish era road bike with centerpull brakes, the right brake recently started squealing pretty badly. the brakes aren't really toe-able as they are right now but as far as i can tell nothing has changed and the rim seems like it's in good condition? i'm not sure if it's dirty or something but i don't really know of anything that would have caused it, and i had been riding it for about two months with no noise.

Andrew R Stewart 

There are many threads on this topic. Some will give advice we will lack to repost so try a search or two.

Brake squeal is from a very high rate of grab/release/grab/release between the pads and the rim. So anything you can do to change the way the pads interact with the rim might be the solution. As bike get ridden they suffer from all kinds of wear, contaminate (oils, grime, dirt, water), pads harden, pad contact surface shape/area with the rim changes, brake pivots change in their slop, rim brake track surface textures change.

I've chased so many noisy brakes and tried all the standard tricks, even less common ones like toe out pads or reversing off center pads on their mounts. The one trick that I have found is a last resort the almost always works is dirt between the pad and rim. Yes, common garden dirt. I suspect this lessens the grib and therefore the release and regrab that's the cycle of a high pitch vibration. Andy